Mohave Community College Libraries

How to Search Databases


Choosing keywords is a critical part of the search process because keywords function as your search terms. In general, keyword searching is what you use when you are first beginning a search.

Unlike Google and other internet search engines that utilize Natural Language Searching, databases are designed to retrieve results that contain every word that has been typed into a search box.

Unless an article or other source contains all the keywords in the search box, the database will not retrieve it as a result. This is why selection of your keywords is very important (more on this in the next section). 

Keywords are the main ideas represented in your research topic or question and/or the main words you would use to describe the topic to another person.

The main steps in the keyword process are:

1. Determine which words or phrases represent the main concepts of your research question

2. Determine synonyms or related words for those concepts

3. Determine which words you are going to combine into a search

Step 1: Read the research question below; the keywords/phrases have been underlined.

  • What is the relationship between children drinking diet soda and weight gain?

Step 2: Determine synonyms or related words/phrases. If you are having trouble, try looking the term up in a thesaurus or encyclopedia to help you generate a list.


Diet Soda

Weight Gain


low calorie soda



diet beverage



diet pop

increased body mass

Step 3: Determine which words you are going to use for your first search. After you have generated a list, you can then pick and choose which words you are going to use to conduct your first search.

However, you are not quite ready to search on a library database yet, because you need to combine your keywords with Boolean Operators in order to conduct a successful search.

Information Literacy Tutorial by Board of Regents of the University of Wisconsin System is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. Based on a work at

Boolean Searching & Boolean Operators

Boolean Searching: Type of search that allows for fewer, but more focused, search results. In other words a Boolean search can filter out information that is irrelevant for your purposes.


Boolean Operators: Words used to connect and define relationships between search terms. Use Boolean operators to narrow or broaden your search. The three primary Boolean Operators are explained below.


Natural Language Searching:  Means you use regular everyday language to ask a question (as if you were asking a person). Internet search engines (such as Google) utilize natural language searching. You cannot use natural language searching in databases.

There are three primary Boolean Operators that databases utilize: AND, OR, NOT.
  • Using the operator AND between search terms means that you will retrieve results that contain both search terms.
  • Using this operator between search terms will decrease (narrow) the number of results you retrieve.

Example: obesity AND soda


  • Using the operator OR between search terms means that you will retrieve results that contain at least one of the search terms. Results may also contain both of the terms. 
  • Using this operator between search terms will increase (broaden) the number of results you retrieve.
  • Use the OR operator when there are synonyms or variations of a word or when you want to search for two or more aspects of the same topic. 

Example: obesity OR overweight


  • Using the operator NOT before a search term means that you will exclude that word from your results. Meaning results that contain that search term will not show up.
  • You may want to use this operator to exclude words or terms that are not relevant to your search or to exclude words that have multiple meanings. It will decrease (narrow) your results.

Example: diet NOT beverage

Phrase Searching and Truncation

Phrase Searching: Use phrase searching to keep words together in a search so the database will search the phrase and not the individual words.

Example: "diet soda" will yield results that contain the exact phrase "diet soda." If you did not use the quotation marks, you could get results that talk about these terms separately i.e. the database would search "diet" AND "soda" instead.

Be careful! You want to use phrase searching on established phrases—meaning on words that you can expect writers to have used. It may not work if you try and use too many words in a phrase search. 

Truncation: Truncation is a search strategy that broadens your search to include various word endings and spellings. In other words, a truncated search tells the database to search for every form of a root word. Both EBSCO and Gale databases use an asterisk (*) to indicate a truncated search.

Use truncation by putting an asterisk * at the end of any root word. 

Example: teen* will yield results that contain teen, teens, teenagers, and teenage

Note: Other databases may use either a question mark (?) or exclamation point (!). You can verify by checking the help or search tips section of the database.


Nesting: Refers to the use of parenthesis to clarify relationships between search terms when using more than one Boolean operator.

"Nesting" is a technique used to retrieve a broad list of search results. Since topic, ideas, and keywords can be expressed in multiple ways (think synonyms), "nesting" can be used to search for several variations of a search term at once. 

Nesting uses parenthesis to group search terms that are alike (like terms) together. The parenthesis also tell the database that you want the terms in the parenthesis looked for first. Nesting also uses the Boolean operator OR to connect "like terms" and the Boolean operator AND to connect the "like terms" to the rest of the search. Confused? See the examples below:

Example 1: (obesity OR overweight) AND "diet soda"

Example 2: (children OR youths OR adolescent OR minors) AND obesity

In both of these examples of nested searches, the database will first find any of the search terms in parenthesis and then look for the term outside the parenthesis.

How does "Nesting" Help me?

1. Broadens your search.

2. Including or excluding parenthesis can give you vastly different results. See the examples below where the same search terms are utilized in searches with and without nesting:

Example 1: obesity AND ("diet soda" OR "diet beverages")
In this example of a search with nesting, you will get search results that include either "obesity and diet soda" or "obesity and diet beverages." 


Example 2: obesity AND "diet soda" OR "diet beverages"
In this example of the same search without nesting, you will get search results that include "obesity and diet soda" or "diet beverages" alone. In other words, because the parenthesis have been omitted, the search term "diet beverages" has been completely separated from the rest of the search. If doing research on this topic you, would get a large number of irrelevant results with this search.

If the database has one search box on the screen and does not have drop down boxes containing Boolean operators, this is known as a "Basic search." Creating a nested search is straight forward in this case.

obesity AND ("diet soda" OR "diet beverages")


In the Basic search example above, I have to manually type in my search terms, Boolean operators, and parentheses all in one search box. Some databases may only have the "Basic search" option available, in which case there is little confusion when creating a nested search.


Many databases provide an "Advanced search" feature, which includes drop down boxes with Boolean operators (AND, OR, NOT) with multiple search boxes to type search terms into (EBSCOhost databases open the "Advanced search" automatically).

An "Advanced search" makes Boolean searching easier for students, but it is also easy to search without using proper nesting (while thinking you are) with this type of search. See the examples below.

Example 3:

Obesity AND "diet soda" OR "diet beverages"

Although it is tempting, you do not want to set your search up like Example 1 because it is not a nested search. You would get results that contained both "obesity and "diet soda" or results that contained "diet beverages" by itself. In other words, the search term "diet beverages" has been completely separated from the rest of the search. If doing research on this topic you, would get a large number of irrelevant results with this search (it is formatted differently but this is the exact same search as Example 2).


Example 4:

obesity AND ("diet soda" OR "diet beverages")

You do want to set your search up like this. Example 4 is a properly formatted nested search. If you used this search you would get results that contained either "obesity and diet soda" or "obesity and diet beverages."


EBSCOhost and Gale Databases support nested searching, but not all databases do. If you are unsure, you can always click on the database "help' link to check or contact a librarian. 

Field Searching

Field Searching: Telling the database what parts of the electronic record or article to search. The majority of databases have the option of "selecting a field" when creating a search.

  • Selecting a search field is optional, but for focused searches, it can increase your chances of finding relevant information.
  • If you do not "select a field" when you search, most databases will search the Title, Abstract, and Subject Headings by default. 
  • Field search options are typically located in a drop-down menu to the right of individual search boxes. If you do not see them, try clicking "Advanced Search."
  • You can mix and match the fields when performing a search.

Advanced search screen from an EBSCOhost database.

What are the common search fields?

  • Author: If you want to find articles written by a particular author, select this field and search by the author's name. Typically, author's have written several articles on the same topic and this is a good way to find additional sources.
  • Title: Search by words you want to appear in the title of search results. Titles of academic articles are typically very descriptive and a search by this field is a good way to focus your search results.
  • Subject Heading: Limit your search to results that are assigned a specific subject heading. Different articles on the same subject will be assigned the same subject heading in a database.
  • Full Text or All Text: Searches every part of the article for your search terms or phrases.
  • ​​​​​​Journal: If you know the information you want is in a specific journal, then limit your search to that journal with this search field.